Chapter 7 done

.gitignore

@@ -1 +1 @@
-/target
+/target/

src/error.rs

@@ -1,7 +1,9 @@
 use thiserror::Error;
 
+use crate::interpreter::Primitive;
 use crate::lexer::Token;
 use crate::misc::CodePos;
+use crate::parser::expr::{BinaryOp, UnaryOp};
 
 #[derive(Error, Debug)]
 pub enum LexerError {
@@ -27,31 +29,55 @@ pub enum ParserError {
     UnexpectedToken { token: Token },
 }
 
+#[derive(Error, Debug)]
+pub enum EvalError {
+    #[error("Unary operator {op} had invalid argument {arg}")]
+    UnaryOpInvalidArgument { op: UnaryOp, arg: Primitive },
+    #[error("Binary operator {op} had invalid arguments {left} and {right}")]
+    BinaryOpInvalidArguments {
+        left: Primitive,
+        op: BinaryOp,
+        right: Primitive,
+    },
+    #[error("Division by zero")]
+    DivisionByZero,
+}
+
 #[derive(Error, Debug)]
 pub enum LoxError {
-    #[error("{msg}")]
-    LexerError { msg: String },
-    #[error("{msg}")]
-    ParserError { msg: String },
+    #[error("{0}", format_lexer_errors(inner))]
+    LexerError { inner: Vec<LexerError> },
+    #[error("{inner}")]
+    ParserError { inner: ParserError },
+    #[error("{inner}")]
+    EvalError { inner: EvalError },
+}
+
+fn format_lexer_errors(lexer_errs: &Vec<LexerError>) -> String {
+    let msg = if lexer_errs.len() == 1 {
+        format!("{}", lexer_errs[0])
+    } else {
+        let msgs: Vec<String> = lexer_errs.iter().map(|err| format!("{}", err)).collect();
+        msgs.join("\n")
+    };
+
+    msg
 }
 
 impl From<Vec<LexerError>> for LoxError {
     fn from(lexer_errs: Vec<LexerError>) -> Self {
-        let msg = if lexer_errs.len() == 1 {
-            format!("{}", lexer_errs[0])
-        } else {
-            let msgs: Vec<String> = lexer_errs.iter().map(|err| format!("{}", err)).collect();
-            msgs.join("\n")
-        };
-
-        LoxError::LexerError { msg }
+        LoxError::LexerError { inner: lexer_errs }
     }
 }
 
 impl From<ParserError> for LoxError {
-    fn from(parser_error: ParserError) -> Self {
-        LoxError::ParserError {
-            msg: format!("{parser_error}"),
-        }
+    fn from(parser_err: ParserError) -> Self {
+        LoxError::ParserError { inner: parser_err }
+    }
+}
+
+impl From<EvalError> for LoxError {
+    fn from(eval_err: EvalError) -> Self {
+        LoxError::EvalError { inner: eval_err }
     }
 }

src/interpreter/eval.rs

@@ -0,0 +1,113 @@
+use std::fmt::Display;
+
+use crate::error::EvalError;
+use crate::parser::expr::{BinaryOp, Expr, Literal, UnaryOp};
+
+pub type EvalResult = Result<Primitive, EvalError>;
+
+/*====================================================================================================================*/
+
+pub fn evaluate(expr: Expr) -> EvalResult {
+    expr.eval()
+}
+
+/*====================================================================================================================*/
+
+#[derive(Debug, PartialEq)]
+pub enum Primitive {
+    String(String),
+    Number(f64),
+    Bool(bool),
+    Nil,
+}
+
+impl Primitive {
+    fn is_truthy(&self) -> bool {
+        match self {
+            Primitive::Bool(false) | Primitive::Nil => false,
+            _ => true,
+        }
+    }
+}
+
+impl Display for Primitive {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Primitive::String(s) => write!(f, "\"{s}\""),
+            Primitive::Number(num) => write!(f, "{num}"),
+            Primitive::Bool(b) => write!(f, "{b}"),
+            Primitive::Nil => write!(f, "nil"),
+        }
+    }
+}
+
+/*====================================================================================================================*/
+
+trait Eval {
+    fn eval(self) -> EvalResult;
+}
+
+impl Eval for Literal {
+    fn eval(self) -> EvalResult {
+        match self {
+            Literal::String(s) => Ok(Primitive::String(s)),
+            Literal::Number(num) => Ok(Primitive::Number(num)),
+            Literal::Bool(b) => Ok(Primitive::Bool(b)),
+            Literal::Nil => Ok(Primitive::Nil),
+        }
+    }
+}
+
+impl Eval for Expr {
+    fn eval(self) -> EvalResult {
+        match self {
+            Expr::Literal(literal) => literal.eval(),
+            Expr::Unary(op, expr) => {
+                let arg = expr.eval()?;
+
+                match (op, arg) {
+                    (UnaryOp::Negate, Primitive::Number(num)) => Ok(Primitive::Number(-num)),
+                    (UnaryOp::Not, Primitive::Bool(b)) => Ok(Primitive::Bool(!b)),
+                    (UnaryOp::Not, primitive) => Ok(Primitive::Bool(!primitive.is_truthy())),
+                    (op, arg) => Err(EvalError::UnaryOpInvalidArgument { op, arg }),
+                }
+            }
+            Expr::Binary(left_expr, op, right_expr) => {
+                use Primitive::{Bool, Number, String};
+
+                let left = left_expr.eval()?;
+                let right = right_expr.eval()?;
+
+                match (left, op, right) {
+                    (Number(left), BinaryOp::Add, Number(right)) => Ok(Number(left + right)),
+                    (Number(left), BinaryOp::Subtract, Number(right)) => Ok(Number(left - right)),
+                    (Number(left), BinaryOp::Multiply, Number(right)) => Ok(Number(left * right)),
+                    (Number(left), BinaryOp::Divide, Number(right)) => {
+                        if right == 0.0 {
+                            return Err(EvalError::DivisionByZero);
+                        }
+                        Ok(Number(left / right))
+                    }
+
+                    (String(left), BinaryOp::Add, String(right)) => Ok(String(left + &right)),
+
+                    (left, BinaryOp::Equal, right) => Ok(Bool(left == right)),
+                    (left, BinaryOp::NotEqual, right) => Ok(Bool(left != right)),
+
+                    (Number(left), BinaryOp::Less, Number(right)) => Ok(Bool(left < right)),
+                    (Number(left), BinaryOp::LessEqual, Number(right)) => Ok(Bool(left <= right)),
+                    (Number(left), BinaryOp::Greater, Number(right)) => Ok(Bool(left > right)),
+                    (Number(left), BinaryOp::GreaterEqual, Number(right)) => Ok(Bool(left >= right)),
+
+                    (String(left), BinaryOp::Less, String(right)) => Ok(Bool(left < right)),
+                    (String(left), BinaryOp::LessEqual, String(right)) => Ok(Bool(left <= right)),
+                    (String(left), BinaryOp::Greater, String(right)) => Ok(Bool(left > right)),
+                    (String(left), BinaryOp::GreaterEqual, String(right)) => Ok(Bool(left >= right)),
+
+                    (left, op, right) => Err(EvalError::BinaryOpInvalidArguments { left, op, right }),
+                }
+            }
+            Expr::Grouping(expr) => expr.eval(),
+        }
+    }
+}

src/interpreter/mod.rs

@@ -0,0 +1,5 @@
+mod eval;
+mod run;
+
+pub use eval::Primitive;
+pub use run::interpreter_main;

src/interpreter/run.rs

@@ -1,6 +1,7 @@
 use std::io::Write;
 
 use crate::error::LoxError;
+use crate::interpreter::eval::evaluate;
 use crate::lexer::{scan_tokens, Token};
 use crate::parser::parser::parse_tokens;
 
@@ -23,9 +24,17 @@ fn run_file(script_path: &str) {
         std::process::exit(66);
     });
 
-    if let Err(err) = run(&source_code) {
+    /* if let Err(err) = run(&source_code) {
         eprintln!("{}", err);
         std::process::exit(65);
+    } */
+
+    if let Err(err) = run(&source_code) {
+        eprintln!("{err}");
+        match err {
+            LoxError::LexerError { .. } | LoxError::ParserError { .. } => std::process::exit(65),
+            LoxError::EvalError { .. } => std::process::exit(70),
+        }
     }
 }
 
@@ -90,5 +99,9 @@ fn run(code_string: &str) -> Result<(), LoxError> {
 
     println!("{expr}");
 
+    let result = evaluate(expr)?;
+
+    println!("{result}");
+
     Ok(())
 }

src/parser/parser.rs

@@ -66,7 +66,11 @@ impl Parser {
     pub fn parse(self) -> ParserResult<Expr> {
         let mut me = self;
 
-        me.expression()
+        let expr = me.expression()?;
+
+        me.consume_token(TokenType::EOF)?;
+
+        Ok(expr)
     }
 
     fn synchronise(&mut self) {
@@ -227,6 +231,12 @@ impl Parser {
     }
 
     fn next_token(&mut self) -> ParserResult<Token> {
+        // let next = self.token_iter.next();
+
+        // println!("Next token: {next:?}");
+
+        // next.ok_or(ParserError::TokenStreamEnded)
+
         self.token_iter.next().ok_or(ParserError::TokenStreamEnded)
     }